Bag for the containing of gas-producing liquid products, in particular yeast

ABSTRACT

Bag for containing liquid products which produce gas, in particular yeast, of the double wall type, includes two opposite faces ( 2 ) joined one to the other along a perimeter heat-sealing line ( 3 ) and a spout ( 7 ) for delivering the liquid product placed on one of these faces ( 2 ), the double wall of the bag including a high permeability inner film ( 5 ) and a reinforcing outer film ( 6 ), wherein at least in the upper part of each of the two opposite faces ( 2 ) of the bag ( 1 ), between the inner film ( 5 ) and the outer film ( 6 ) at least one spacer element ( 10 ) is provided, attached to the outer film ( 6 ) at one at least opening ( 19 ) formed therein and provided with holes ( 17 ) for the release of the gases which permeate through the inner film ( 5 ).

FIELD OF THE INVENTION

The object of the present invention is a bag for the containing of liquid products which emanate gas, in particular yeasts for bread making

BACKGROUND FOR THE INVENTION

In the following description specific reference will be made to yeast, but it is to be understood that the invention can be applied to any liquid or paste product which during storage emanates gas.

Yeast, in the phase of production, is always in the liquid state and, for the placing on the market, in the majority of cases, is subsequently dehydrated in order to transform it into powder or into the form of solid cakes. In the phase of use the yeast has once again to be returned to the liquid form.

In recent times there has been the tendency to produce and package the yeast directly in liquid form which is advantageous from practical and economic standpoints in that the phases of transformation from the liquid state to the solid state during production and vice versa during use are eliminated.

The problem in the storage of the liquid yeast is that it emanates a considerable quantity of gas, in particular CO₂, up to 1-3 litres a day for a package of 10/20 litres.

Bags are therefore necessary which on the one hand are highly permeable to the gases and on the other hand have adequate toughness for sustaining the weight of the content, these bags normally having a capacity of 10/20 litres.

In order to meet these needs “double wall” bags have therefore been proposed, i.e. having a polyethylene-based inner film highly permeable to CO₂, with very thin thickness (30-50 μm) and therefore with little mechanical strength, and an outer film constituted by a nylon-based laminate, with thickness of 80-150 μm, suitable for conferring the necessary mechanical strength to the bag.

The outer film, which is not permeable, has a plurality of small holes to allow the release of the gases which permeate through the inner film.

The bag shaped in this way is placed inside a cardboard box in such a way as to constitute a so-called bag-in-box packaging which can easily be manipulated.

The bags of the aforementioned type have not proved to be satisfactory in that despite the providing of the perforated outer film an unsatisfactory release of the gases which tend to inflate the bag has been noted.

This is due to the fact that when the bag filled with liquid yeast is inserted in the cardboard box it adapts to the box, causing a pressure contact between the outer surface of the bag and the inner walls of the box, apart from the head space of the bag which remains clear.

This pressure contact causes a strong adherence between the inner and outer plastic films of the bag, practically clogging the holes provided in the outer film and preventing therefore the release of the gases, which tend to accumulate in the upper part of the bag, where they have difficulty in exiting due to the small perforated surface of the outer film not in contact with the inner wall of the containing box.

SUMMARY OF THE INVENTION

The object of the invention is that of eliminating the aforesaid disadvantages of the prior art.

More particularly an object of the invention is that of providing a bag for liquid yeasts which allows a complete and rapid degassing of the product contained therein.

Another object of the present invention is that of providing such a bag which is simple and economical to manufacture.

The bag according to the invention has the features of the annexed independent claim 1.

Advantageous embodiments of the invention are disclosed by the dependent claims.

Substantially the bag according to the invention, of the so-called double wall type, comprises a polyethylene-based inner film with high permeability and a nylon-based outer reinforcing laminate, wherein at least in the upper part of each face of the bag, between the inner film and the outer film, at least one spacer element is provided between these films attached perimetrically to an opening formed in the outer film and provided with holes for the release of the gas.

Advantageously this spacer element comprises a perforated body having a perimeter edge heat-sealed to said outer film and a possible seat of housing of a cover or cap, also perforated.

Preferably the inner film of the bag is a coextruded LLDPE of 30 μm (28 g/m²), while the outer film is a laminate comprising a layer of OPA (nylon) of 15 μm (17 g/m²), placed between two layers of coextruded LLDPE-EVA of 38 μm (35 g/m²).

The outer layers with LLDPE (linear low density polyethylene) polyethylene base allow the heat sealing of the outer film to the inner film, also with a polyethylene base, and the heat sealing of the spacer elements to the outer film, while the intermediate layer of OPA (oriented polyamide) confers toughness to the bag.

BRIEF DESCRIPTION OF DRAWINGS

Further features of the invention will be made clearer by the following detailed description, referred to one of its embodiments purely by way of a non-limiting example illustrated in the accompanying drawings, in which:

FIG. 1 is a schematic plan view of the bag according to the invention;

FIG. 2 is an enlarged section view along line II-II of FIG. 1 involving one single face of the bag;

FIG. 3 is a section enlarged to a lesser extent with respect to FIG. 2, taken along line III-III of FIG. 1;

FIG. 4 is a schematic perspective view of the bag of FIG. 1.

DETAILED DESCRIPTION OF INVENTION

Referring to these drawings, the bag according to the invention, for the containing of liquid products which emanate gas, in particular yeast, has been denoted by reference numeral 1.

It comprises two opposite faces 2, joined by means of perimeter heat sealing 3, which runs parallel to its outer edge 4.

In the accompanying drawings the bag 1 has been illustrated rectangular in shape, which is the simplest to make, but it is clear that it can take on any other shape.

The bag 1 is of the so-called double wall type, in the sense that each of its two opposite faces 2 comprises two films, an inner one 5 and an outer one 6, separated one from the other and joined only at said perimeter heat-sealing line 3.

On one of the two faces 2 of the bag 1 a spout 7 for filling/delivering of the product is applied, having a circular base flange 8 sealed internally to the corresponding face 2, while the spout 7 projects through a hole formed in this face, and is closed by a cap 20.

The inner film 5 of the double wall of the bag is with high permeability to gases, in particular to CO₂ which is produced in a large quantity by the yeast contained in the bag, >50 l/m² day atm. It has a base of polyethylene, for example a coextruded LLDPE and has a very thin thickness (30 μm) in order to be able to obtain the aforesaid high values of permeability.

Such a film would alone be very fragile and therefore subject to easy tearing. Therefore the outer film 6 is assigned the task of conferring toughness to the bag and avoiding easy breaking

This outer film 6 is normally a laminate with several layers, for example comprising:

-   -   a first layer of 38 μm of coextruded LLDPE-EVA of 35 g/m²;     -   a second layer of 15 μm of OPA (nylon) of 17 g/m²;     -   a third layer of 38 μm of coextruded LLDPE-EVA of 35 g/m²;

Naturally the number of the layers of the laminate constituting the outer film 6 can be different with respect to that illustrated, provided they contain a layer with high toughness, such as the layer of OPA (nylon) and at least one polyethylene-based outer layer, in order to allow performance of the perimeter heat sealing 3, as well as the heat sealing of the base 8 of the spout 7, and the heat sealing of spacer elements 10 between the inner film 5 and outer film 6 of each face 2 of the bag 1, as now will be described in greater detail.

In fact, to avoid the two films adhering one to the other when the bag 1 is inserted in a containing box (bag-in-box) normally in cardboard, at least in the upper part of each face 2 of the bag, substantially at the level of the delivering spout 8, a spacer element 10 is placed which on the one hand allows the films 5 and 6 of the corresponding face 2 to be kept distanced and on the other hand the gas, in particular CO₂, to be released through the outer film 6.

In FIGS. 1 and 4 the spacer element 10 to the left of the spout 7 is provided on the front face of the bag, while the element to the right of the spout, in a dotted line in FIG. 1, on the rear face.

Referring to the enlarged section of FIG. 2, it is noted that the spacer element 10 has a base body 11 with a seat 12 for housing a cover or cap 13, and a perimeter edge 14, sealed to the inner surface of the outer film 6.

According to the embodiment illustrated in FIG. 2, both in the base wall 15 and in the side wall 16 of the base body 11 holes 17 are provided, and corresponding holes 18, 28 are provided in the cap 13, so that the gas, in particular carbon dioxide, produced by the yeast contained in the bag 1, which permeates through the inner film 5, can be evacuated by passing through the aforesaid holes 17, 18, 28 and an opening 19 or corresponding holes provided in the outer film 6 at said cap 13.

The spacer element 10 shown in FIG. 2 is obtained by modifying a one-way degassing valve of the same Applicant, wherefrom a diaphragm has been removed which prevents the flow of gas from the exterior to the interior and wherein the additional holes 17, 28 have been formed.

It is however clear that the spacer element 10 can take on any configuration, without detriment to its function of keeping the films 5 and 6 separate and allowing the release of gas through it.

More particularly in the embodiment illustrated the cap 13 can be eliminated in that not necessary, providing a plurality of holes in the outer film 6 in place of a single opening 19.

Practical tests performed have demonstrated that a single spacer element such as the one described and illustrated, placed on each face 2 of the bag 1, in the upper part of the bag, where the gases emanated by the product contained in the bag tend to collect, is sufficient for evacuating the CO₂ released by the yeast.

It is however clear that, if necessary, several spacer elements 10 can be provided on the opposite faces of the bag 1.

Although, according to the invention, the outer film 6 is provided as continuous, i.e. without holes, it is clear that it could also be perforated, like those of the prior art.

In this case several spacer elements 10 could be provided, not perforated, distributed over the surface of the faces of the bag, suitable for keeping distanced the films 5, 6 and allowing the release of the gas through the holes provided in the outer film 6.

From what has been disclosed the advantages appear clear of the invention which allows, with simple and economical means, the complete and rapid release of the CO₂ gas produced by the liquid contained in the bag 1.

Naturally the invention is not limited to the particular embodiment previously described and illustrated in the accompanying drawings, but instead numerous detail changes can be made thereto, within reach of the person skilled in the art, without thereby departing from the scope of the same invention as defined in the annexed claims. 

1. Bag for containing liquid products which produce gas, in particular yeast, of the double wall type, comprising two opposite faces (2) joined one to the other along a perimeter heat-sealing line (3) and a spout (7) for filling/delivering the liquid product placed on one of these faces (2), the double wall of the bag comprising a high permeability inner film (5) and a reinforcing outer film (6), characterised in that at least in the upper part of each of said two opposite faces (2) of the bag (1), between said inner film (5) and said outer film (6), at least one spacer element (10) is provided, attached to the outer film (6) at one at least opening (19) formed therein and provided with holes (17) for the release of the gases which permeate through said inner film (5).
 2. Bag according to claim 1, characterised in that said spacer element (10) comprises a base body (11) provided with said holes (17), having a perimeter edge (14) sealed to the outer film (6) so as to enclose said at least one opening (19) in the film (6).
 3. Bag according to claim 2, characterised in that said holes (17) are formed both in the base (15) and in the side wall of said base body (11).
 4. Bag according to claim 2, characterised in that it further comprises a cap (13) provided with holes (18, 28), housed in a seat (12) of said base body (11).
 5. Bag according to claim 1, characterised in that said inner film (5) is based on polyethylene and said outer film (6) contains at least one layer of OPA (nylon).
 6. Bag according to claim 5, characterised in that said outer film (6) is a laminate comprising at least one intermediate layer of OPA sandwiched between polyethylene-based outer layers.
 7. Bag according to claim 6, characterised in that said laminate of the outer film (6) comprises: a first layer of coextruded LLDPE-EVA, a second layer of OPA and a third layer of coextruded LLDPE-EVA.
 8. Bag according to claim 7, wherein the layers of the laminate of the outer film have the following thicknesses and weights: coextruded LLDPE-EVA, 38 μm; 35 g/m²; OPA (nylon), 15 μm; 17 g/m²; coextruded LLDPE-EVA, 38 μm; 35 g/m².
 9. Bag according to claim 5, characterised in that said inner film (5) is a LLDPE coextruded of 30 μm and 28 g/m².
 10. Bag according to claim 1, characterised in that said outer film (6) is perforated.
 11. Bag according to claim 3, characterised in that it further comprises a cap (13) provided with holes (18, 28), housed in a seat (12) of said base body (11). 